NASA unveiled the first photos from Comet Tempel 1 flyby on 2011 Valentine's day by Stardust-NExT mission. Tempel1 was first visited back in 2005 during Deep impact mission, where a space probe was crashed into Tempel1 to basically study its composition, which as per NASA's stated mission objective was "To study the pristine interior of a comet by excavating a crater more than 25 m deep and 100 m in diameter". The following flyer gives an insight into what the previous mission was about.
Comet Tempel1 orbits the sun once every 5-1/2 years. The objective of this mission is to study the changes in Comet's exterior since the last impact in 2005.
The photo below shows Tempel1 during the recent flyby courtesy NASA.